Conventionally, in order to ensure durability against a high temperature generated in company with combustion, or durability against contamination and degradation in company with a chemical reaction such as a vapor phase reaction at a distal end and in a flow path, a burner made of quartz glass as a material has been known especially as a combustion burner for heat processing. In order to form a flow path in a quartz glass burner, however, a skilled artisan had to manually fabricate the burner from a quartz glass tube as starting materials taking a long time. Especially, a quartz glass burner with many flow paths has been fabricated using many quartz glass tubes as starting materials by a skilled artisan in such a way that the quartz glass tubes are deliberately processed one by one and thereafter the quartz glass tubes are accurately bundled into a single body to thereby complete the quartz glass burner.
However, since such a quartz glass burner is manually fabricated, there have inevitably arisen variations in dimensional precision between product lots and therefore a necessity has occurred for various settings or adjustments for heat processing in each lot of the burners by a scent of an operator manipulating a burner.
Therefore, as disclosed in, for example, JP A 2000-104908, a method has been proposed in which a burner head is mechanically and integrally machined from a quartz glass rod according to a boring method using a drill.
The inventors have continuously investigated and developed uses of the fabrication method, and have repeated serious studies on application thereof to a single hole burner nozzle and a multihole burner of a straight type which were mainly fabricated from metals such as stainless steel, iron, brass or copper in the prior art. As a result, the present invention has been achieved.
That is, conventionally, a metal single hole burner especially used for local heat processing lacks problematically agile operability because it is heavy for an operator, and more than anything else, when heat processing is continued for long time, since a distal end of the metal burner is overheated by reflecting heat from a workpiece, a phenomenon unavoidably occurs that spray of the metal or metal ions from the distal end may be stuck or migrated to the workpiece.
Even in case of no heat processing, when liquids high in corrosiveness and reactivity, for example, strong acids such as hydrochloric acid or strong bases such as caustic soda, or gases high in reactivity such as silicon tetrachloride are fed to the nozzle, an inconvenience inevitably occurs that the metal itself is corroded.
In view of the above, while a quartz glass single hole burner has been employed in a specified field, the burner is not of a type fabricated by directly drilling a high purity synthetic quartz glass rod with a boring diameter precisely set in such a way as disclosed in the present invention; therefore, flow control thereof cannot be necessarily performed with a high precision, and it requires various kinds of adjustment operations based on a scent of an operator manipulating the burner. Especially, in recent years, the heat processing utilizing a robot has been tried. In this case, if the heat processing is operated placing the burner at a fixed position and setting the other operating conditions, there are severely demanded uniformity in performance and reproducibility of a product of the burner itself, with which a complete measure for coping has been requested.
Moreover, when the distal end of the burner is broken by contact with a workpiece, an expensive quartz glass burner has to be totally replaced with a new one; measures to solve the problem have been awaited in various aspects. In a micro-processing field, for example, when a syringe drug glass ampoule for medical use is heat sealed, since a nozzle diameter is especially small, slight dimensional errors result in a difference in a feed rate of fluid; a quantitatively exact specification has been required. A precise specification has been similarly required in an ordinary micro-welding field as well.
Since JP A 2000-104908 described above discloses such a construction as convergence of a gas flow is indispensable, it has been also demanded to fabricate a multihole burner of non-convergence (in which feed paths are parallel to each other) which is employed, for example, in flame processing. However, since it has been difficult to fabricate the multihole burner maintaining an exact straight advance of drilling for boring, a problem has remained that fabrication of the multihole burner involves difficulty.
The inventors have continuously investigated and developed uses of the fabrication method, and found it to apply the method to a single hole burner head and a multihole burner of straight type which were mainly fabricated from metals such as stainless steel or copper in the prior art. As a result, the present invention has been achieved.